MEMS devices are widely used and may include membrane type sensors and bulk silicon sensors. Bulk silicon sensors with a large proof-mass may provide motion sensors with high mechanical sensitivity. However, fabrication of membrane type sensors using a bulk silicon structure is difficult because the high stiffness of the bulk silicon structure does not provide sensitivity needed by membrane type sensors. Furthermore, combinations of CMOS wafers and MEMS wafers may cause an out-gassing issue that diffuses hydrogen (H2) from the PECVD oxide. The subsequent pressure level shift within the MEMS device induced by the hydrogen may degrade the performance of the devices.